Many buildings have lighting systems. For example, many commercial buildings include fluorescent lighting fixtures for use with fluorescent tubes, though other types of lighting systems using other types of lights (e.g., incandescent lights) may also be used. Fixtures are typically hard-wired to a power source, such as an electric utility line. The lighting system may produce a generally constant flux of light so long as a switch controlling the lighting system is in an “on” position. Typically, the sole function of lighting systems is providing light.
Many buildings also have one or more sound systems. For example, an alarm sound system may be part of an alarm system for notifying building occupants of an emergency. While alarm sound systems may include emergency lighting, the emergency lighting is typically active only during the emergency to supplement the notice of the emergency provided by the alarm sound. The emergency lighting included with some sound systems, such as a strobe light, is typically not designed to provide normal lighting for a building. Another type of sound system includes speakers for making announcements. Such speakers typically do not include lighting. Sound systems, including both the alarm sound system and announcement speakers, typically are separate from and operate independently of lighting systems.
Many buildings also have one or more cameras for security purposes. Most cameras are separate from and operate independently of both lighting systems and sound systems.